Characterising the Frequency Ripple in Antenna Noise Temperature Using Exponential Analysis

This paper presents a method for characterising the ripple observed in the antenna noise temperature of reflector systems as a function of operating frequency. The ripple, which is superimposed on the dominant power-law shape, must be accurately characterised in order to determine its impact. Traditional methods, such as Fourier transform analysis, typically involve some preprocessing to reduce the effect of the power law, which may inadvertently introduce additional ripple components. To overcome this limitation, it is shown how the Validated EXPonential Analysis (VEXPA) method can be used without the need to remove the trend of the curve. The results demonstrate that VEXPA produces accurate results and is therefore a valuable alternative to traditional methods.